diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+ GNU GENERAL PUBLIC LICENSE
+ Version 3, 29 June 2007
+
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+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+
+ Copyright (C)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see .
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ Copyright (C)
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+.
+
+
diff --git a/SGdemo.cabal b/SGdemo.cabal
new file mode 100644
--- /dev/null
+++ b/SGdemo.cabal
@@ -0,0 +1,23 @@
+name: SGdemo
+version: 1.0
+synopsis: An example of using the SG and OpenGL libraries
+description: This program serves as a demonstration of the functions of the SG library
+ (to be found on Hackage:
+ )) by
+ visualising it with OpenGL. It also serves as a sort of informal test
+ suite for the SG library. Documentation is available at
+ the top of the main module's source code.
+category: Graphics
+license: GPL
+license-file: LICENSE
+author: Neil Brown
+maintainer: neil@twistedsquare.com
+copyright: Copyright (c) 2009, Neil Brown
+stability: Provisional
+build-depends: base, SG, OpenGL, GLUT
+build-type: Simple
+
+executable: sgdemo
+main-is: SGdemo.hs
+ghc-options:
+extensions: MultiParamTypeClasses FlexibleContexts
diff --git a/SGdemo.hs b/SGdemo.hs
new file mode 100644
--- /dev/null
+++ b/SGdemo.hs
@@ -0,0 +1,399 @@
+-- SGdemo; a demonstration of the SG library
+-- Copyright (C) 2009, Neil Brown
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program. If not, see .
+
+
+-- | This program serves as a demonstration of the functions of the SG library
+-- (to be found on Hackage:
+-- )) by
+-- visualising it with OpenGL. It also serves as a sort of informal test
+-- suite for the SG library.
+--
+-- The demonstration has a persistent state of placed shapes, lines and points,
+-- which you can interact with.
+--
+-- There are four different modes of operation:
+--
+-- * Place shape (press 's'). Your cursor will shown you the shape to be placed.
+-- You can alter the shape type by scrolling your mouse-wheel (for those without
+-- mouse wheels, the up and down cursor keys can be used). Intersections with
+-- lines are shown by black crosses. If you intersect another shape, black
+-- lines will indicate the results of the overlap function, drawn from the centre
+-- of each shape.
+--
+-- * Place line (press 'l'). At first you have a cross cursor. You can left-click
+-- to place the start of the line there. Then, your cursor shows a prospective
+-- line from the start point. Intersections with shapes are shown with black crosses.
+-- A purple line will be drawn from each point to the line, indicating the shortest
+-- path from the line to each point. Intersections with other lines are shown with
+-- a black circle, and a blue line indicates the output of the reflectAgainstIfNeeded2
+-- function, reflecting the prospective line against the pre-existing-line-as-surface-normal.
+--
+-- * Place point (press 'p'). Your cursor becomes a dashed circle, and left-clicking
+-- will place a point there permanently. Points are mainly useful when you later
+-- switch to line mode.
+--
+-- * Rotate (press 'r'). Your cursor indicates a straight line from the centre.
+-- If you left-click, that line will become the new upwards vertical, and everything
+-- in the world will be rotated to match.
+--
+-- If in doubt, take a look at the code -- that's what it's there for!
+module Main (main) where
+
+import Data.SG
+
+import Control.Arrow
+import Control.Monad
+import Data.IORef
+import Data.Maybe
+import Graphics.Rendering.OpenGL hiding (Polygon, multMatrix)
+import Graphics.UI.GLUT hiding (cursor, Polygon, Solid, multMatrix)
+import qualified Graphics.Rendering.OpenGL as GL
+import Prelude hiding (lines)
+
+-- Define our own versions of the SG types using the openGL double type:
+type Point2 = Point2' GLdouble
+type Rel2 = Rel2' GLdouble
+type Line2 = Line2' GLdouble
+type Shape = Shape' GLdouble
+
+-- Allow for easy conversion from a Point2 type into an openGL 2D vertex:
+instance IsomorphicVectors Point2' Vertex2 where
+ iso (Point2 (x, y)) = Vertex2 x y
+
+-- Helper function for drawing a point as an openGL vertex
+vertex' :: Point2 -> IO ()
+vertex' v = vertex (iso v :: Vertex2 GLdouble)
+
+-- Draws a cross at the given point:
+drawCross, drawSmallCircle :: Point2 -> IO ()
+drawCross p = renderPrimitive Lines $ do
+ -- First line:
+ vertex' $ p `plusDir` makeRel2 (-0.01, 0.01)
+ vertex' $ p `plusDir` makeRel2 (0.01, -0.01)
+ -- Second line:
+ vertex' $ p `plusDir` makeRel2 (0.01, 0.01)
+ vertex' $ p `plusDir` makeRel2 (-0.01, -0.01)
+drawSmallCircle p = renderPrimitive GL.LineStrip $ drawCircle (p, 0.01)
+
+-- Just draws the points; you choose the primitive outside!
+-- Draws the first point at the end again (effectively).
+drawCircle :: (Point2, GLdouble) -> IO ()
+drawCircle (c, r) = mapM_ vertex' ps
+ where
+ ps = map (c `plusDir`) $ regularPoints 32 r
+
+-- Includes the first point twice, effectively. Gives back N points spaced equally
+-- around the origin with the given radius. So a low number (e.g. 3) will serve
+-- as a regular polygon; higher numbers begin to approximate a circle.
+regularPoints :: Integer -> GLdouble -> [Rel2]
+regularPoints numPoints r
+ = reverse antiClockwisePoints -- We need clockwise points for polygons
+ where
+ angleToDir t = scaleRel r $ makeRel2 (cos t, sin t)
+
+ antiClockwisePoints = map angleToDir angles
+ -- Equally spaced points, starting at 90 degrees (straight-up) and going all
+ -- the way around.:
+ angles = [(2*pi * (t / fromInteger numPoints)) + (pi/2)
+ | t <- [0 .. fromInteger numPoints]]
+
+-- We draw shapes empty when considering placing them, and solid when placed:
+data DrawAs = Solid | WireFrame
+
+drawShape :: DrawAs -> Shape -> IO ()
+drawShape Solid (Circle c r)
+ = renderPrimitive GL.TriangleFan $ vertex' c >> drawCircle (c, r)
+drawShape WireFrame (Circle c r)
+ = renderPrimitive GL.LineStrip $ drawCircle (c, r)
+drawShape Solid s = renderPrimitive GL.Polygon $ mapM_ vertex' $ shapePoints s
+drawShape WireFrame s = renderPrimitive GL.LineLoop $ mapM_ vertex' $ shapePoints s
+
+-- Draws a line, with a cross at the start:
+drawLine, drawLineNoCross :: Line2 -> IO ()
+drawLine l = drawCross (getLineStart l) >> drawLineNoCross l
+drawLineNoCross l = renderPrimitive Lines $ do
+ vertex' (getLineStart l)
+ vertex' (getLineEnd l)
+
+-- Current mode we are in:
+data Mode = PlaceShape Integer | PlaceLine (Maybe Point2) | PlacePoint | Rotate
+ deriving (Show)
+
+-- Makes a shape. Pass numbers in the range 2 or higher, where 2 is a circle:
+makeShape :: Integer -> Point2 -> Shape
+makeShape 2 p = Circle p 0.03
+makeShape 4 p = Rectangle p (0.05, 0.03)
+makeShape n p = Polygon p $ init $ regularPoints n 0.04
+
+data WorldState = WorldState
+ { shapes :: [Shape]
+ , lines :: [Line2]
+ , points :: [Point2]
+ , cursor :: Point2
+ , curMode :: Mode
+ }
+ deriving (Show)
+
+rotateWorld :: GLdouble -> WorldState -> WorldState
+rotateWorld a w = w
+ { shapes = [(rotateShape a s) {shapeCentre = rot (shapeCentre s)}
+ | s <- shapes w]
+ , lines = [uncurry makeLine $ rot *** rot $ getLineVecs l
+ | l <- lines w]
+ , points = map rot $ points w
+ }
+ where
+ rot :: (IsomorphicVectors Pair p, IsomorphicVectors p Pair) => p GLdouble -> p GLdouble
+ rot = multMatrix m
+ m :: Matrix22' GLdouble
+ m = rotateZaxis a
+
+startWorld :: WorldState
+startWorld = WorldState [] [] [] origin PlacePoint
+
+-- Like mapMaybe, but keeps the original alongside the mapped version:
+mapMaybe' :: (a -> Maybe b) -> [a] -> [(a, b)]
+mapMaybe' f xs = [(x, y) | (x, Just y) <- map (id &&& f) xs]
+
+-- Short for in-range-zero-to-one:
+zo :: GLdouble -> Bool
+zo x = 0 <= x && x <= 1
+
+-- Given a shape, draws stuff for anything that shape might intersect with:
+drawAllIntersectShape :: Shape -> WorldState -> IO ()
+drawAllIntersectShape s w
+-- Draw everything that might intersect with a shape: other shapes, lines
+ = do let intersectionsWithLines
+ = [map (`alongLine` l) -- Turn them back into points
+ $ filter zo [a,b] -- Only those in bounds
+ | (l, (a, b)) <- mapMaybe' (`intersectLineShape` s) $ lines w]
+ currentColor $= slColour
+ sequence_ [drawCross p | p <- concat intersectionsWithLines]
+ currentColor $= ssColour
+ sequence_ [do drawLine (makeLine (shapeCentre s) a)
+ drawLine (makeLine (shapeCentre s') b)
+ | (s', (a, b)) <- mapMaybe' (overlap s) $ shapes w]
+
+-- Given a line, draws stuff for anything that line might intersect with:
+drawAllIntersectLine :: Line2 -> WorldState -> IO ()
+drawAllIntersectLine l w
+-- Draw everything that might intersect with a line: shapes, other lines (TODO points)
+ = do let intersectionsWithShapes
+ = [map (`alongLine` l) -- Turn them back into points
+ $ filter zo [a,b] -- Only those in bounds
+ | (s, (a, b)) <- mapMaybe' (l `intersectLineShape`) $ shapes w]
+ currentColor $= slColour
+ sequence_ [drawCross p | p <- concat intersectionsWithShapes]
+ sequence_ [do let intersectPoint = a `alongLine` l
+ reflectedDir = getLineDir l `reflectAgainstIfNeeded2` getLineDir l'
+ currentColor $= llColour
+ drawSmallCircle intersectPoint
+ currentColor $= reflectColour
+ drawLineNoCross $ makeLine intersectPoint reflectedDir
+ | (l', (a, b)) <- mapMaybe' (intersectLines2 l) $ lines w
+ , zo a -- Must be in bounds
+ , zo b -- of both lines
+ ]
+ currentColor $= lpColour
+ -- Draws points that are exactly on the line. Note that this is unlikely
+ -- to happen, even if it looks like it should. Also, this is indistinguishable
+ -- (at the moment) from the nearest point case below.
+ sequence_ [drawCross p | p <- points w, p `isOnLine` l]
+
+ sequence_ [let dist = (p `nearestDistOnLine` l)
+ in when (zo dist) $ drawLine $ (dist `alongLine` l) `lineTo` p
+ | p <- points w]
+
+
+-- Draws everything in the world:
+drawWorld :: WorldState -> IO ()
+drawWorld w = do currentColor $= drawnColour
+ mapM_ (drawShape Solid) $ shapes w
+ mapM_ drawLine $ lines w
+ mapM_ (renderPrimitive GL.LineStrip . drawCircle . (id &&& const 0.01)) $ points w
+ currentColor $= draftColour
+ -- Draw cursor according to current mode (e.g. shapes)
+ case (curMode w) of
+ PlaceShape n -> do let s = makeShape n (cursor w)
+ drawShape WireFrame s
+ currentColor $= Color4 0.2 0.2 0.5 0
+ drawAllIntersectShape s w
+ PlaceLine (Just p) -> do let l = cursor w `lineFrom` p
+ drawLine l
+ currentColor $= Color4 0.2 0.2 0.5 0
+ drawAllIntersectLine l w
+ PlaceLine Nothing -> drawCross (cursor w)
+ Rotate -> drawLineNoCross $ cursor w `lineFrom` origin
+ -- All other modes:
+ -- Deliberately leave gaps in cursor by drawing as lines:
+ _ -> renderPrimitive GL.Lines $ drawCircle (cursor w, 0.02)
+
+ currentColor $= textColour
+ drawStatusText (text w)
+
+text :: WorldState -> [String]
+text w = (case curMode w of
+ PlaceShape n -> ["SHAPE: " ++ shapeName n
+ ,"Mousewheel: change shape"
+ ,"Left click: place shape"]
+ PlaceLine Nothing -> ["LINE", "Left click: place start"]
+ PlaceLine (Just _) -> ["LINE", "Left click: place end"]
+ PlacePoint -> ["POINT", "Left click: place point"]
+ Rotate -> ["ROTATE", "Left click: set new vertical"]
+ ) ++ modes
+ where
+ shapeName 2 = "Circle"
+ shapeName 3 = "Triangle"
+ shapeName 4 = "Rectangle"
+ shapeName n = show n ++ "-sided"
+
+ modes = ["s: Shape Mode"
+ ,"l: Line Mode"
+ ,"p: Point Mode"
+ ,"r: Rotate Mode"
+ ]
+
+-- Draws the given status text.
+drawStatusText :: [String] -> IO ()
+drawStatusText strLines = preservingMatrix $ do
+ matrixMode $= Modelview 0
+ loadIdentity
+ let toDouble = fromInteger . toInteger
+ let targetWidth = 0.4
+ origWidth <- liftM (maximum . map toDouble) $ mapM (stringWidth Roman) strLines
+ let sc = targetWidth / origWidth
+ lineWidth $= 2
+-- lineSmooth $= Enabled
+ sequence_ [ do translate $ Vector3 0.1 (0.2 + (150 * sc * n)) 0
+ scale sc sc (1 :: GLdouble)
+ renderString Roman s
+ loadIdentity
+ | (n, s) <- zip [0..] $ reverse strLines]
+
+draftColour, drawnColour, reflectColour, slColour, ssColour, llColour, lpColour,
+ textColour :: Color4 GLclampf
+textColour = Color4 0 0 0.5 0
+-- For things relating to the cursor:
+draftColour = Color4 1 0 0 0
+-- For things now in the world properly:
+drawnColour = Color4 1 0.25 0.5 0
+-- For reflective lines:
+reflectColour = Color4 0 0 1 0
+-- For shapes intersecting lines:
+slColour = Color4 0 0 0 0
+-- For shapes intersecting shapes:
+ssColour = slColour
+-- For lines intersecting lines:
+llColour = slColour
+-- For lines nearest to points:
+lpColour = Color4 0.75 0.25 0.75 0
+
+processWorld :: Key -> WorldState -> WorldState
+processWorld k ws = case (k, curMode ws) of
+ -- Mode changes:
+ (Char 'l', _) -> ws { curMode = PlaceLine Nothing }
+ (Char 'p', _) -> ws { curMode = PlacePoint }
+ (Char 's', _) -> ws { curMode = PlaceShape 2}
+ (Char 'r', _) -> ws { curMode = Rotate}
+
+ -- Point placement:
+ (MouseButton LeftButton, PlacePoint)
+ -> ws { points = cursor ws : points ws }
+
+ -- Shape placement:
+ (MouseButton WheelUp, PlaceShape 2)
+ -> ws
+ (MouseButton WheelUp, PlaceShape n)
+ -> ws { curMode = PlaceShape $ pred n }
+ (MouseButton WheelDown, PlaceShape n)
+ -> ws { curMode = PlaceShape $ succ n }
+
+ (SpecialKey KeyUp, PlaceShape 2)
+ -> ws
+ (SpecialKey KeyUp, PlaceShape n)
+ -> ws { curMode = PlaceShape $ pred n }
+ (SpecialKey KeyDown, PlaceShape n)
+ -> ws { curMode = PlaceShape $ succ n }
+
+ (MouseButton LeftButton, PlaceShape n)
+ -> ws { shapes = makeShape n (cursor ws) : shapes ws }
+
+ -- Line placement:
+ (MouseButton LeftButton, PlaceLine Nothing)
+ -> ws { curMode = PlaceLine $ Just $ cursor ws }
+ (MouseButton LeftButton, PlaceLine (Just p))
+ -> ws { curMode = PlaceLine Nothing
+ , lines = (cursor ws `lineFrom` p) : lines ws }
+
+ -- Rotation:
+ (MouseButton LeftButton, Rotate)
+ -> rotateWorld (negate (toAngle (cursor ws `fromPt` origin)) + (pi/2)) ws
+
+ -- Anything else:
+ _ -> ws
+
+glRunAs2D :: IO () -> IO ()
+glRunAs2D draw = do
+ matrixMode $= Modelview 0
+ loadIdentity
+
+ matrixMode $= Projection
+ loadIdentity
+
+ ortho (-0.5) 0.5 (-0.5) 0.5 (-1000) 1000
+
+ preservingMatrix draw
+
+main :: IO ()
+main = do
+ world <- newIORef startWorld
+
+ -- Create the window:
+ initialWindowSize $= Size 500 500
+ getArgsAndInitialize
+ initialDisplayMode $= [DoubleBuffered]
+ _window <- createWindow "SGdemo"
+
+ -- Register callbacks:
+ let translate :: Position -> IO Point2
+ translate (Position x y)
+ = do (_, Size w h) <- get viewport
+ return (Point2 ( (conv x / conv w) - 0.5
+ , negate (conv y / conv h) + 0.5))
+
+ conv = fromInteger . toInteger
+ moveCursor p = do w <- readIORef world
+ writeIORef world $ w { cursor = p }
+
+ passiveMotionCallback $= Just (\pos ->
+ translate pos >>= moveCursor >> postRedisplay Nothing)
+
+ keyboardMouseCallback $= Just (\k st _ pos ->
+ do translate pos >>= moveCursor
+ when (st == Down) $
+ modifyIORef world $ processWorld k
+ postRedisplay Nothing)
+
+ displayCallback $= (glRunAs2D $ do
+ clearColor $= Color4 1 1 1 1
+ lineWidth $= 1
+ lineSmooth $= Disabled
+ clear [ColorBuffer, DepthBuffer]
+ readIORef world >>= drawWorld
+ flush
+ swapBuffers)
+
+ mainLoop
diff --git a/Setup.lhs b/Setup.lhs
new file mode 100644
--- /dev/null
+++ b/Setup.lhs
@@ -0,0 +1,3 @@
+#!/usr/bin/env runhaskell
+> import Distribution.Simple
+> main = defaultMain